1. Field of the Invention
The present invention relates to an article pickup apparatus and an article pickup method for recognizing a position and a posture of an article disposed in a three-dimensional space and for picking up the recognized article using a robot.
2. Description of the Related Art
As an apparatus of this type, conventionally, there is known an apparatus configured to recognize a position of an article by pattern matching with respect to a two-dimensional image obtained by imaging articles disposed in a three-dimensional space using a camera or a three-dimensional point set obtained via measurement using a three-dimensional measurement instrument. Such an apparatus is described, for example, in Japanese Laid-open Patent Publication No. 2004-295223 (JP2004-295223A) and Japanese Laid-open Patent Publication No. 2011-179909 (JP2011-179909A). Further, there is also known an apparatus configured to extract an article in an image using image data obtained by imaging articles disposed in a three-dimensional space using a camera. An apparatus of this type is described, for example, in Japanese Laid-open Patent Publication No. 2010-039999 (JP2010-039999A).
In the apparatus described in JP2004-295223A, a two-dimensional model pattern is prepared from a two-dimensional image obtained by previously imaging an article in a standard three-dimensional relative posture, and then a plurality of transform two-dimensional model patterns are prepared by applying two-dimensional geometric transform to the two-dimensional model pattern to perform two-dimensional pattern matching with respect to a two-dimensional image of an article using the plurality of transform two-dimensional model patterns.
In the apparatus described in JP2011-179909A, while a three-dimensional model pattern of an article is previously acquired from a CAD model or the like, surfaces of articles in a three-dimensional space are measured using a three-dimensional measurement instrument and a three-dimensional point set (a distance image) is acquired, and then the three-dimensional point set is divided into partial regions surrounded by an edge extracted from the three-dimensional point set. Then, initially, one of the partial regions is set as an article region, and both matching processing of the three-dimensional model pattern for the article region and update processing for adding another partial region to the article region are repeated to measure positions and postures of the articles.
In the apparatus described in JP2010-039999A, a color image and a distance image of a region including an article are acquired by an imaging operation of a camera, and then the acquired images are displayed on a display part. When a part of the article in the displayed image is taught by a user as a foreground region, a region other than the article is set as a background region based on color information of a color image and distance information obtained from a distance image to extract the article in the image.
However, in the apparatuses described in JP2004-295223A and JP2011-179909A, it is necessary to previously prepare a two-dimensional model pattern or a three-dimensional model pattern for each kind of articles, resulting in a need for time and effort. In particular, when there are a large number of different articles, it is necessary to prepare model patterns corresponding to the number of different articles, and therefore, much time and effort are necessary.
In the apparatus described in JP2010-039999A, in order to extract an article in an image, a teaching operation by a user is necessary, resulting in a need for time and effort. In particular, when there are a large number of different articles, it is necessary to perform teaching operations corresponding to the number of different articles, and therefore, much time and effort are necessary.